Measuring the Obliquities of the TRAPPIST-1 Planets with MAROON-X

Abstract

A star's obliquity with respect to its planetary system can provide us with insight into the system's formation and evolution, as well as hinting at the presence of additional objects in the system. However, M dwarfs, which are the most promising targets for atmospheric follow-up, are underrepresented in terms of obliquity characterization surveys due to the challenges associated with making precise measurements. In this paper, we use the extreme-precision radial velocity spectrograph MAROON-X to measure the obliquity of the late M dwarf TRAPPIST-1. With the Rossiter-McLaughlin effect, we measure a system obliquity of $-2_{-19}^{+17}$ degrees and a stellar rotational velocity of 2.1 $\pm$ 0.3 km s${}^{-1}$. We were unable to detect stellar surface differential rotation, and we found that a model in which all planets share the same obliquity was favored by our current data. We were unable to make a detection of the signatures of the planets using Doppler tomography, which is likely a result of the both the slow rotation of the star and the low SNR of the data. Overall, TRAPPIST-1 appears to have a low obliquity, which could imply that the system has a low primordial obliquity. It also appears to be a slow rotator, which is consistent with past characterizations of the system and estimates of the star's rotation period. The MAROON-X data allow for a precise measurement of the stellar obliquity through the Rossiter-McLaughlin effect, highlighting the capabilities of MAROON-X and its ability to make high-precision RV measurements around late, dim stars.

18 pages, 6 figures, submitted to AJ

References in corpus (24)

• Array Programming with NumPy
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• Stellar obliquities in exoplanetary systems
• Orbital misalignment of the Neptune-mass exoplanet GJ 436b with the spin of its cool star
• Python Leap Second Management and Implementation of Precise Barycentric Correction (barycorrpy)
• The New Generation Planetary Population Synthesis (NGPPS). III. Warm super-Earths and cold Jupiters: A weak occurrence correlation, but with a strong architecture-composition link
• A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs
• The CARMENES search for exoplanets around M dwarfs. Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
• The Warm Neptune GJ 3470b has a Polar Orbit
• Limits on the Spin-Orbit Angle and Atmospheric Escape for the 22 Myr-old Planet AU Mic b
• The Habitable-zone Planet Finder Reveals A High Mass and a Low Obliquity for the Young Neptune K2-25b
• A backward-spinning star with two coplanar planets
• Solar Obliquity Induced by Planet Nine
• Evidence for Spin-orbit Alignment in the TRAPPIST-1 System
• On-sky commissioning of MAROON-X: A new precision radial velocity spectrograph for Gemini North
• Development and construction of MAROON-X
• Outer-planet scattering can gently tilt an inner planetary system
• Hot Stars With Kepler Planets Have High Obliquities
• MAROON-X: The first two years of EPRVs from Gemini North
• Habitable planet formation around low-mass stars: Rapid accretion, rapid debris removal and the essential contribution of external giants
• Rotational modulation of spectroscopic Zeeman signatures in low-mass stars
• System Architecture and Planetary Obliquity: Implications for Long-Term Habitability
• Changes in orientation and shape of protoplanetary discs moving through an ambient medium
• Stellar winds as a mechanism to tilt the spin axes of Sun-like stars

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• The First Spin-Orbit Obliquity of an M dwarf/brown dwarf System: An eccentric and aligned TOI-2119 b
• Mapping the Skies of Ultracool Worlds: Detecting Storms and Spots with Extremely Large Telescopes
• The Aligned Orbit of a Hot Jupiter around the M Dwarf TOI-4201
• ASTEP confirmation of a pair of long-period Jupiter-sized planets with extremely low densities transiting TOI-791